Apparatus for damping mineral fibers to be sprayed in air



y 22, 1952 N. L. DOLBEY 2,604,068

APPARATUS FOR DAMPING MINERAL FIBERS TO BE SPRAYED IN AIR Filed May 25, 1949 4 Sheets-Sheet 2 7 F/GZ IHIHI, I WWI l '-4o T:

3s 6 42 T r lllllllllllllllllIII IDIII'IIIII f 50 Q I I OI I I I 3 I mm I 35 22 Inventor 8 1:2 g I AI orne v N. DOLBEY 2,604,068 APPARATUS FOR DAMPING MINERAL FIBERS TO BE SPRAYED IN AIR 4 Sheets-Sheet 4 July 22, 1952 Filed May 25, 1949 Inven tor Norma/7 lou/ls fia/hey B 22 4 V Aiorney Patented July 22, 1952 UNITED APPARATUS FOR DAMPING MINERAL FIBERS TO BE SPRAYED IN AIR Norman Louis Dolbey, Armley, Leeds, England, assignor to J. W. Roberts Limited, Armley, Leeds, England, a British company Application May 25, 1949, Serial No. 95,208 In Great Britain October 2, 1946 '10 Claims. 1

This application is a continuation-impart of my co-pending application Serial No. 776,964, filed September 30, 1947. r

A very effective way of forming insulating coatings on walls, ceilings or other surfaces is to spray asbestos fibre with or without other material and with an adhesive or ingredients which react to form an adhesive.

This process can advantageously be carried out in the manner and with the apparatus described in Patents Nos. 1,990,584 and 1,990,585 issued to me, the fibre being suspended in air and then sub jected to suction but when this is done-there is one practical drawback. This drawback is that dust escapes into the atmosphere during the sprayingoperation and, in order to overcome it, many expedients have been tried. The drawback can be overcome by the method described in my application Serial No; 603,616, now Patent No. 2,563,457, that is to'say, by mixing the asbestos with a predetermined quantity of water or other damping material in such a way that in the course of the mixing substantially every particle of asbestos is damped and the damping material is so :uniformly distributed throughout the asbestos that there is no tendency for particles to stick together by reason of different moisture contents. In my said application No. 603,616 I have alsodescribed apparatus by which this process can be carried out, this apparatus incorporating a rotary mixing drum adapted to carry the asbestos upwards as thedrum rotates and a rotary brush mounted within the drum to engage the, asbestos which is carried upwards and by a beating action to open .up fibre bundles and fling the particles through the drum to fall to the bottomand be carried upwards again. Such an apparatusserves to treat batches of asbestos fibre. Now it is desirable to be able to work continuously, that is to say, to feed dry asbestos to an apparatus such as that shown in my Patents Nos. 1,990,584 and 1,990,585 and to spray it Without having to damp the fibre in'batches.

An object of this invention is to provide novel means for supplying asbestos or other mineral fibre, e. g. glass fibre, to be supplied in a current of air to a spraying device in a substantially dustfree state.

Another object of the invention is to provide improved means for damping asbestos or other fibres.

, As a result of many researches, I have found that the dust can be reducedto such an extent that ,the drawback is largely overcome, although the formation and spraying'of dust may not be 2 completely eliminated. To achieve this result I spray the fibre with water or other damping agent while it is travelling in a thin layer and before it is suspended in air, I control the damping in accordance with the fiow of fibre, and in feeding the damped fibre particles into the air current I prevent suction being exerted to any substantial extent on such dust as is formed so thatpractically no such dust is drawn into the air current.

It is important that the dampingshould be as uniform as possible and for this reason the fibre should be spread out into a thin layer, that is to say, one thinner than is usual atthe present time. The dampin agent sprayed on to this layer may be water in atomised form, oil or any appropriate liquid. It is simplest to use water, and the water jets should be as fine as possible. In addition to damping the thin layer of fibre, such jets also create a fog-like atmosphere which tends to cause any dust formed to settle within the apparatus. 3

I effect the damping, in a casing through which the thin layer travels and which is substantially closed, and it is an important feature that the interior of this casing is not. in communication with any space under low pressure such that dust in suspension in the, casing would be drawn out of it by suction.

The apparatus according to this invention is preferably of the general kind shown in my Patents Nos. 1,990,584 and 1,990,585, that'is to'say, it includes a conveyorbelt to carry the fibreupwards past a brush which serves to remove all the fibre except the desired thin layer. I modify this apparatus by providing means for spraying atomised water onto thethin layer while it is still on the conveyor belt, the layer being removed from the belt by a stripping brush. The thinner the layer of fibre which is sprayed with the water the better the results, as the fibre and water become more uniformly mixed. It is possible to make the layer thinner without reducing the capacity of a given apparatus by increasing the speed of the conveyor and making the first brush approach the conveyor closely. I find it impossible to damp the fibre absolutely uniformly while it is on the conveyor and accordingly a little dust is produced by the action of thefstripping' brush and conveyed to the sprayin device. However, this dust is relatively small in amount and .to keep it to a minimum the speed of the stripping, brush should be made as low as possible.

'In' the apparatus described'in myPatents Nos. 1,990,584 and 1,990,585, the air into which the particles are projected-is 'drawn into the suction inlet of a fan, so in effect the particles form a suspension in a moving current of air and this suspension is conveyed forward by the fan. In that apparatus it is the fan which produces the greatest part of the dust. In the present invention I may still use a fan but-by the time the fibre'arrives at the fan it is already sufficiently damped to prevent any appreciable formation of further dust in the fan.

So far as possible, no dust should bedrawn for.-

ward with the fibre and, to this endyl prefer to modify the apparatus further. In the first place,

4 ered by a hood 1 hinged at 8 to the upper corner of the hopper 3.

Asbestos fibre is charged into the hopper 3,

and is delivered by the apparatus to a nozzle 9 r for use as required. The bottom of the hopper is formed by an endless belt it carried on rollers H and I2. The roller'l I is carried" on a split shaft l3, I4 and contains an epicyclic gear l5.

Thus while the shaft [3 is driven continuously by an electric motor I6 through the belt I! and pulley I8, the roller II will be held stationary by friction unless the shaft is is locked. When when I employ a fan to conveythe suspension forwards, I prefer to cause the fan todraw-in air from the atmosphere so that the suction I which it produces is not exerted to any-substan-; tial extent upon the interior of the casing. This, result is preferably attained by providing fan with an inlet duet inclined upwards "to its open end, and admitting fibre to the duct at a point below the open end. Air enters the. duct opposite direction to the shaft 13.

it is so locked, the roller II will rotate in the The roller 1'2 is carried in bearings I9 whereby the tension ofthebelt maybe adjusted. The belt l9 itself iswider than the hopperand carries over the A width of the hopper a series of spikes 28. When freely from ,the atmosphere and then: entrains the fibre' without settingup any suction. which would draw air, from within the apparatus.

Instead of causing the particles to pass through a fanI may entrain theminan air current which may itself be produced by-a fan. For instance, the, particles on being projected into air by a stripping brush may fall: downa furmel-like' duct to a continuously rotating valve of the star or gate type, through. which the particles pass into a pipe in which theair current is flowing. Such wh'enever'spraying is] stopped. In the present invention; thespray of atomisedwater, oil or 'otherJdamping agent may be stopped simultaneously under the same control. The preferred form of apparatus according to the invention will now be described byway of example with reference'to the accompanying drawings in which I V r V Figure 1' shows .an elevation ofone side-of the apparatus with the hood'partly broken away, and the beltcasing removed.

Figure 2 shows an elevation of one-end of th apparatus.

Figure 3 shows a plan view of part'of the apparatus with the hood removed.

7 Figure 4 shows a vertical section of the upper the outside of these channelsare side plates 2, e

and above and within thechannels a hopper 3.

' Above the*p1a tes 2 are additional.smallJp-lates.

9, 5 outside the channels andjplates j.6.-i, nside the chann Thetop of.t apparatusisgcov the. interior of the casthe shaft M is locked, the conveyor is driven to carry asbestos upwardstowards the roller l I.

At the top corner of the hopper 3; a cylindrical brush 21, is carried in adjustable bearings 22. This brush rotates close to-the surface of the belt and serves to remove excess asbestos and return it to the hopper-sothat aathin layer of asbestosis carried intoa substantially. closed chamber under the hood l. The brush is fitted with a cleaning comb 23. The layer of asbestos is sprayed with water from-a row of nozzles 24, and is then carried beneath asecondcylindrical brush 25., This is rotated, at a speed. just suflicient to remove damped asbestos from the belt l9, and drop it intoachutegzt'. The brushes are driven by two chains. 21, 28 from the shaft i3. One of the nozzles 2,4,is shown in section in Figure 7. They, are fedwith compressed air through pipes 29 and 30, a control valve. 31,.and pipes 32 and 33. The airservestodraw water from a carburettor 35 throughpipestfi and. 31. Water is supplied to thedcarburettor fro'in aninlet 34.

The asbestos falling into the chute. 26,v is: de-

7 livered to the inclined,inletg ductfid' of a-fanttfl.

This duct is open to theatniosphere 2317.40; sothat the fan does not. tend to suck airgfromlthe body of the" apparatus. The: fanisdrivenfrom the motor. I6 througha belt tLnormally coveredby a casing 42. It delivers the. asbestos in a stream of airthrough a hose 43 to the nozzle 9.- On discharge 'it encounters asprayfrom a nozzle-"i=3 supplied with water and compressed'air through pipes 45, it. and a-valve 4 7. 1 Compressed air, having passed the valve, is also-led-oft through a pipe 68. to-the: pipe 29- on theside of the apparatus. This not only supplies airgto-the nozzles 24, but also operates a plunger. S in acylinder 50. This enters one of a'number offholes-fl inthe periphery. of a wheel 52-,on 'theshaft l l and so causes the motor to drive the belt 10 Thus operation of the valve 41 startsandstops the supply of asbestos, of damping spray, andspray at the discharge, while allowing the fan-39'andbrushes iii, 25 to run continuously to' prevent choking of the apparatus. r I r I claim: 7 r

-1. In anapparatus for usein applying aninsulating coating of V asbestos to a surface by spraying, the combination of a casing, aconveyor adapted to carry asbestos in athinlayer through said casing, means-in said'casing 'forspraying said layer with a damping liquid, a brushfor stripping said layerwhen damped-fromsaid con,- veyor, a discharge chute placed to-receive pare .ticlesstripped-from said conveyor, means for'setting. up a. current of .aiixto carryaway said par- -:2, mana paratus for use in applyingan insulating coating of' asbestos to a surface by spraying,the combination of ahopper, a damping; chamber, an inclined conveyor belt form-f ing'successi'vely the bottom ofsaid hopper. and the bottom-of said damping chamber and'adapt edto ',c'onvey asbestos upwards from saidhopper to'said damping chamber," means for reducing the asbestos conveyed to a thin layer, said means separating said hopper from said chamber, means for spraying damping liquid onto said layer in said chamber, a discharge chute, a rotary brush separating said chamber from said discharge chute, means for rotating said brush relatively to said conveyor whereby to strip asbestos as particles from said conveyor and to deliver said particles to said chute, and a fan for setting up a current of air at the lower end of said chute to carry away said particles, said current being at the lower end of said chute at substantially the same pressure as air within said chamber.

3. Apparatus for damping asbestos fibre to be applied as an insulating coating comprising a conveyor, rotary brushes operating close to said conveyor, a plurality of nozzles for spraying a damping agent, a fan blowing said fibre to a discharge nozzle and pneumatic control means operative by a single controlling movement to stop the movement of said conveyor, and the spraying of said damping agent simultaneously, while permitting said brushes and said fan to rotate continuously.

4. Apparatus for damping asbestos fibre comprising a substantially enclosed damping chamber, a spiked conveyor belt carrying said fibre to said damping chamber, spraying means for supplying atomised water to said chamber, a cylindrical rotary brush, means for rotating said brush to detach said fibre from said conveyor and means for setting up a current of air at substantially the same pressure as that within said chamber, whereby said detached fibre is carried away without entraining air from said chamber.

5. Apparatus for damping asbestos fiber to be applied as an insulating coating, comprising a conveyor for the fiber, means for spraying a damping agent onto the fiber on said conveyor, rotary means for stripping the fiber from said conveyor, a fan blowing said fiber to a discharge nozzle, and controlling means operative by a single controlling movement to stop the movement of said conveyor and spraying of said damping agent simultaneously, while permitting said rotary means and said fan to rotate continuously. 1

6. In apparatus for use in applying a coating of asbestos to a surface by spraying, a casing, an air duct, means providing a substantially enclosed passageway from the interior of said casing to the interior of said duct, a conveyor in the casing adapted to carry asbestos in a thin layer through the casing toward said passageway, means in the casing for spraying said layer with a damping liquid, a rotary brush operative to strip said layer when damped from said conveyor and discharge the asbestos particles through said passageway into said air duct, means producing a current of air through said duct for carrying the asbestos particles in the air stream, said duct being open to the atmosphere ahead of the junction of said passageway with the duct whereby substantially no suction fisexerted on the interior. of. said casing by said air current producingmeans. 7In apparatus for use in applying a coating of asbestos toa surface by spraying, a casing, an air .duct, means providing .a. substantially enclosed passageway from the interior .of said casing to the interior of said duct, a conveyor in the casing adapted to carry asbestos in a thin layer through the casing toward said passageway, means in the casing for spraying said layer with a damping liquid, a rotary brush operative to strip said layer when damped from said conveyor and discharge the asbestos particles through said passageway into said air duct, air moving means for advancing a stream of air through said duct past the mouth of said passageway thereby to carry away the asbestos particles in the air stream, said air moving means being connected to said duct on one side of the mouth of said passageway, and said duct being open to the atmosphere on the other side of the mouth of said passageway, whereby the air pressure in said casing is substantially uninfiuenced by the action of said air moving means.

8. In an apparatus for use in applying a coating of asbestos to a surface by spraying, an air duct open at both ends to the atmosphere, air moving means connected to said duct for drawing air into one end thereof and discharging it from the other end, a casing, means providing a substantially enclosed passageway from the interior of the casing to the interior of said air duct, said passageway joining said duct intermediate the air inlet end and the air discharge end thereof whereby the air travels across the mouth of said passageway with relatively little disturbance of the air in the passageway proper and in the casing, a conveyor in said casing adapted to carry asbestos in a thin layer through the casing toward said passageway, means in the casing for spraying said layer with a damping liquid, and a brush operative to strip said layer when damped from said conveyor and discharge the asbestos particles through said passageway into said duct.

9. In an apparatus for use in applying a coating of asbestos to a surface by spraying, an air duct having an inlet and an outlet, means for moving air through said duct from the inlet to the outlet, a casing, means providing a substantially enclosed passageway from the interior of the casing to the interior to said air duct, said passageway joining said duct at a point intermediate the inlet and outlet where the air pressure in said duct is substantially atmospheric, a conveyor in said casing adapted to carry asbestos in a thin layer through the casing toward said passageway, means in the casing for spraying said layer with a damping liquid, and a rotary brush operative to strip said layer when damped from said conveyor and discharge the asbestos particles through said passageway into said duct.

10. In an apparatus for use in applying of asbestos to a surface by spraying, an air duct, a fan in said duct for moving the air therethrough, a casing, means providing a substantially enclosed passageway from the interior of the casing to the interior of said air duct, said passageway joining said air duct on the upstream side of said fan, and said duct being open to the atmosphere on the upstream side of said pas:- sageway whereby substantially no suction is exerted on the interior of the casing by said fan, a conveyor in said casing adapted to carry as- :bestos' in' 2; thin layer. through" the casing. toward said passageway, means invthe casing for'spray ingsaid layer. with a damping liquid, and a, rota'ry brush operative to strip said layer when dampedfrom said conveyor and discharge the asbestos 1 particlesthrough said passageway into said duct. I NORMAN LOUIS DOLBE'Y.

V 7 REFERENCES CITED The following references are of record in the file of thispaitenfiz' v UNITED .STATES PATENTS.

Number Name Date Potter Aug. 14, 1894 I Poston July8, 1930 Hill S'ept. 18, 1934 Dolbey" 'Feb. 12, 1935 Dolbey nsu Feb'.1"2, 1935 Herring Oct; 29,1935 Bramsen Mar; 16, 1937 Hill Jan. 21, 1941 Maurer Apr; 22,1947 

